1. Field of the Invention
A new and useful process is disclosed. The process is directed to the making of thermoplastic polymer fibrilla or fibril. Both products are useful for mixing with cellulosic pulp thereby enhancing the properties of a resulting paper article. Also multicomponent thermoplastic polymer fibrilla and fibril are disclosed.
2. Background Art
U.S. Pat. No. 3,227,784, issued Jan. 4, 1966, discloses a process for direct production of ultramicrocellular structures and/or plexifilamentary products from a thermoplastic polymer solution. The solution is extruded through a suitable orifice or other equivalent means.
U.S. Pat. No. 3,081,519, issued Mar. 19, 1963, discloses a process for the production of integral, multi-fibrous, bulky strands directly from fluid polymer.
U.S. Pat. No. 3,032,384, issued May 1, 1962, discloses a process for production of thermoplastic polymer fibers from a relatively dilute solution of the polymer and a low boiling solvent. The process involves the use of a spinning orifice which causes the filaments that come through orifices to be spun together into a yarn.
U.S. Pat. No. 3,902,957, issued Sept. 2, 1975, discloses a process for the manufacturing of polymeric fibers involving the forming of a mixture of polymer and a solvent for such polymer and flashing said mixture. The flashing is at a temperature high enough to bring the polymer to a plastic state and permits substantially complete vaporization of the solvent when the mixture is flashed. Also, a processing step is disclosed in which the previously formed fibers are subjected to a light shredding action.
West German Patent publication 2458-390, publication date July 24, 1975, according to Central Patent Index by Derwent Publication Ltd., Index No. 51182W/31, discloses short fibril production from a two phase mixture composed of a melted polymer and solvent. The production involves passing the mixture, at high temperature and pressure, through an orifice. During the mixture's passage and expansion through the orifice it is subjected to turbulent flow and afterwards the solvent evaporates and the polymer solidifies.
Belgium Pat. No. 823-578, publication date June 19, 1975, (Derwent Index No. 44398W/27), discloses the production of short polyolefin fibers by dissolving the polyolefin in pentane, or a mixture containing pentane, under pressure, at a temperature above the boiling point of the pentane at atmospheric pressure. Then the solution is passed through an opening into a zone maintained at a lower pressure. The amount of the pentane present is such that the polyolefin separates in the form of discrete short fibers. Also, Belgium Pat. No. 823-440, (Derwent Index No. 4436W/27), publication date June 17, 1975, discloses a similar process and indicates other polymers can be used.
South African Patent 7400-893, publication date Nov. 11, 1974, Derwent Index No. 66237V/39, discloses the manufacture of discontinuous fibrils. The manufacture involves suddenly releasing the pressure acting on a two-phase mixture comprising molten polymer and solvent. The temperature and pressure of the mixture is such that when the pressure is released the solvent is instantaneously vaporized and the polymer solidified. The mixture is ejected at high speed through the orifice in such a way as to form an ejection cone which is atomised.